Magnetic door latch



July 14, 1959 Filed Oct. 6, 1953 J. E. LUNDHOLM MAGNETIC DOOR LATCH 4 Sheets-Sheet 1 INVENTOR.

J'OSEF E. LUNDHOLM Y ATTORNEYS July 14, 1959 J. E. LUNDHOLM 2,894,778

MAGNETIC DOOR LATCH Filed Oct. 6, 1953 4 Sheets-Sheet 2 INVENTOR.

JOSEF E. LUNDHOLM BY m ,zafi

ATTORNEY y 14, 1959 J. E. LUNDHOLM 2,894,778

MAGNETIC DOOR LATCH Filed Oct. 6, 1953 4 Sheets-Sheet s [/Q 9 [/Q/O INVENTOR. JOSEF E. LUNDHOLM ATTO July 14, 1959 J. E. LUNDHOLM MAGNETIC DOOR LATCH Filed Oct. 6. 1953 4 Sheets-Sheet 4 /QIZ 32 35 43 45 48 AVG ll INVENTOR. IOSEF E. LU

NDHOLM r E ATTORNEYS United States Patent MAGNETIC DOOR LATCH Josef E. Lundholm, Lidingo, near Stockholm, Sweden Application October 6, 1953, Serial No. 384,415

Claims priority, application Sweden December 31, 1952 1 Claim. (Cl. 292-2515) The present invention relates to a lock, for instance a door lock, consisting of two members, which magnetically attract each other.

The object of the invention is to improve the magnetic locks hitherto known in such manner that the magnetic attraction is brought into effect on a great distance from the position of the final locking, whereby the risk of the door or the like standing ajar is reduced.

Said object has been attained according to the invention by providing the attraction surface of one of the magnetic members with a part which at beginning of the closing arrives nearer the other member than the remaining part of the attraction surface of the first mentioned member and therefore earliest make contact with a part of the attraction surface of the other member and closes a magnetic circuit, so that the remaining attraction surfaces attract each other with increased power and bring about the closing, the surface part of the first mentioned member being so displaced that the closing may take place.

Consequently the object of the invention is to improve the known locks in such manner that by use of a magnet of a certain dimension the attraction power between "the magnet and an armature at closing the door or the like to be locked by means of the lock will be sufficient to draw the door or the like into entirely closed position earlier than at known magnetic locks, whereby the risk of the door or the like standing ajar is reduced.

The annexed drawings illustrate useful embodiments of the invention hereinafter described and claimed.

Figs. 1, 2, 3, 7 and 8 show a first embodiment of the lock.

Figs. 4 to 6 show a second embodiment.

Figs. 9 and 10 show a third embodiment.

Figures 11 to 13 show one embodiment of a holder for the armature.

Figures 14 to 16 show a case for the magnet.

According to the embodiments shown in Figs. 1 to 10 the locks are applied on a door 1 together with a corresponding door-frame 2, against which the door 1 is closed along the surface 25 in Figs. 7 and 10. The magnet is a permanent magnet 11 with poles 9 and 10. The magnet 11 is attached to the door 1 by means of screws or the like. The magnet 11 consists of an alloy with a high coercive power. The magnet is U-shaped or in the form of a short rod with embossed parts on the two ends of one of the longitudinal sides, said parts forming the pole surfaces 9 and 10 which lie substantially in one plane. The pole it) lies vertically under the pole 9. The other magnetic member consists in all embodiments of soft magnetic material and is therefore called armature. The armature is applied in a case 3 (Figs. 7 to 10), which is attached to the frame 2 by means of screws 5, which extend through oblong apertures 6 in a projecting part 4 of the case 3, whereby the armature at the mounting may be secured on a desired distance from the magnet 11 at completely closed position of the door.

2,894,778 Patented July 14, 1959 The embodiment according to Figs. 1, 2, 7 and 8 is described in detail as follows.

Figs. 1 to 3 show the different relative positions of the magnet 11 and the armature at the closing, and Figs. 7 and 8 show the lock mounted on a door with door-frame. Figs. 1, 2, 3 and 7 show the lock seen from one and the same side. Fig. 8 shows a section along the line A-B in Fig. 7.

The armature 12 consists of an oblong rectangular plate, provided with an aperture 7 at one of its ends, through which aperture extends a horizontal shaft 8 carrying the armature. The shaft 8 is mounted in an opening in the case 3 and is retained in the case by means of a suitable device. The shaft 8 is positioned higher than the pole 9, whereby, at turning the armature against the pole 10, the armature also approaches the pole 9.

The aperture 7 has a greater diameter than the shaft 8 in order that the armature may be displaced upwards perpendicularly to the shaft, so that the armature does not need to slide on the magnet at the continued closing movement.

In Fig. 1 the door is assumed to be opened so much that the magnet is at such distance from the armature that the same is not influenced by the magnet. The armature in this case depends vertically.

In Fig. 2 the door and the magnet has been turned against the frame so much that the lower end of the armature has been attracted by the magnet, and a surface part of the armature has made contact with a surface part of the magnet, viz. the rounded lower edge of the pole 10 of the magnet.

By said contact the attraction between the pole 9 and the armature is increased. By the attraction between the pole 9 and the armature the magnet thereupon is drawn nearer the armature, until the door is entirely closed.

Fig. 3 shows the position when the door is entirely closed. The position of the case and the armature is such that at complete closing of the door the pole 9 does not entirely contact with the armature, but a space 19 is left between the pole 9 and the armature. After closing therefore the armature 12 is pressed against the shaft 8, as shown in Fig. 7, whereby the door 1 is constantly pressed against the frame 2.

The case 3 is provided with an aperture 23, in which a bar 22 may be inserted, when the case is to be attached to the frame 2, so that a suitable distance 19 is obtained between the pole surface 9 and the armature 12 at complete shutting. The case namely is mounted such that the armature is pressed against the bar 22, when themagnet is pressed against the armature. By use of a bar 22 of suitable diameter the desired distance may be obtained. The bar 22 is removed after use.

In the embodiment according to Figs. 4 to 6 the shaft 18 for turnably suspending of the armature is positioned lower than the pole 9 but higher than the pole 10 but nearer the pole 9 than the pole 10. Thereby the end 17 of the armature at turning the same against the pole 10 will be removed from the pole 9.

According to the embodiment shown in Figs. 9 and 10 the armature 23 is suspended on the shaft 8 so that, as shown in Fig. 9, already when the armature 23 is not yet attracted by the magnet 11 the lower end of the armature is turned out in direction towards the magnet. This is performed by that the aperture 7 for the shaft 8 is positioned in an angular part 24 of the armature. At the first part of the closing movement, when the magnet 11 ap proaches the armature the same at first makes contact with the lower pole 10 of the magnet. At further closing movement the armature 23 is turned to the position shown in Fig. 10.

At the first part of the closing movement the lower portion of the armature may possibly be turned in direction against the magnet so that an earlier contact is obtained. However, this is not necessary and may be prevented by a special stop (not shown).

In the embodiments shown in Figures 11 to 13, the axle of the armature is perpendicular to the longer sides of the armature. Figure 11 is a side view of the holder and the magnet. Figure 12 shows the holder seen from the magnet indicated with dashed and dotted lines. Figure 13 is a top view corresponding to Figure 11.

In the Figures 11 to 13 the holder is denoted 32, and the armature turnable in said holder is denoted 12. The

magnet 11 is supposed to be positioned at such distance ture is mounted. The shorter sides of the holders are denoted 43 and 44, the longer sides 33 and 34 and the bottom 35. The axle 3 is perpendicular to the longer sides 33, 34 and is secured in holes in said sides. The longer sides 33, 34 are provided with oblong apertures 37 and 38, 39 and 40, 41 and 42 for screws extending through the case. The shorter sides 43, 44 of the holder 32 are provided with attaching screws extending through the holder. The bottom 35 of the holder is provided with apertures 48, 49, 50 for attaching the holder by means of screws extending through the bottom 35. The apertures in the sides of the holder permit attaching of the holder by means of screws extending through the apertures without the necessary turning of the armature being prevented by the screws. It should be noted that generally no space is necessary for turning the armature towards the interior of the case. On the other hand, a space is necessary for turning the armature extension 52, which turns towards the interior of the case, when the armature 12 is turned outwards.

According to the above description the holder together with the armature are adapted to be applied on an arbitrary place on a door frame. However, the same advantageous possibility does not exist regarding the magnet, so that it easily may be mounted on said places on the door frame, when the armature has been mounted on the door frame, for instance at use of the apertures, 48, 49, 50in Figures 11 to 13.

However, according to an improvement of the invention the magnet may be applied in a case of such shape that said attaching to the door frame is permitted and also the mounting of the magnet on the door may be performed in a simple manner.

Figures 14 to 16 show an embodiment of a case for mounting the magnet on the appertaining member. Figure 14 shows the case seen from a longer side. Figure is a top view of the case, and Figure 16 shows the case seen from a short side.

The case 60 has substantially square cross section and is open at the top. The magnet 11 is positioned in the middle of the case 60 on the bottom 61 of the same, and

the poles 9, 19 of the magnets extend somewhat above the upper edge 62 of the case 69. The inner width of the case is the same as the width of the magnet. The magnet is pressed against the bottom 61 of the case by means of two flaps 65, 66 bent inwards from the longer sides 63, 64 and downwards into contact with the lower top surface 67 between the poles of the magnet. The flaps 65, 66 have the same width as the space between the poles in order to prevent sliding of the magnet along the case. Thus, the magnet is secured in the case.

The magnet only takes a part of the longitudinal inner space of the case. The case ends extending outside the magnet serve to attach the same to one of the members above mentioned. For this reason the longer sides 63, 64 of the case at each end are provided with apertures 68, 69 and '79, 71 respectively, for screws extending through the case and serving to secure the case with one side pressed against the member, and furthermore the bottom 61 of the case is provided with oblong apertures '72, 73 for attaching the bottom 61 of the case at the member.

Having thus described my invention, 1 claim:

A magnetic door latch for a door member mounted to close relatively to a door frame member, said latch comprising a permanent magnet adapted to be mounted on one of said members and including two projecting poles whose pole faces are coplanar, and a flattened armature adapted to be mounted on the other of said members in such a manner that when the door is in a closed position it is attracted by the two pole faces of the magnet, said armature being pivotally mounted on a shaft extending substantially transversely to the direction in which the door closes and parallel to the plane of the magnet pole faces when the door is closed, the shaft mounting the armature being positioned considerably closer to one pole of the magnet than to the other pole and supporting the armature in such position as the armature approaches the magnet that in closing the door the armature will swing into contact with the magnet pole more remote from the shaft before the door is completely closed causing a decrease of the total length of air-gap and a consequent increase of the force of magnetic attraction, the pivotal mounting of the armature being formed with clearance between the shaft and the armature to provide that on closing of the door sliding of the armature on the magnet pole surface which first attracts it is minimized.

References Cited in the file of this patent UNITED STATES PATENTS 478,245 Smith July 5, 1892 2,497,697 Smith Feb. 14, 1950 2,519,435 Byrd Aug. 22, 1950 2,673,111 Teetor Mar. 23, 1954 2,673,755 Asp Mar. 30, 1954 2,690,922 Teetor Oct. 5, 1954 2,792,249 Saxton May 14, 1957 FOREIGN PATENTS 693,564 Great Britain July 1, 1953 

